Transmit 4

http://www.panic.com/transmit/

A mi lo que más me ha gustado es esto:

Put your favorites in the Finder.

With the new Transmit Disk feature, you can now mount any of your favorites in the Finder itself, even if Transmit's not running. These volumes are real: drag files to your SFTP server, save a small graphic to your Amazon S3 bucket directly from Photoshop, or roll your own iDisk-like backup volume. It's all possible in T4